linux-kernel - Re: [PATCH 08/12] ima: Shallow copy the args_p member of ima_rule

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Message-ID: <1593119917.27152.399.camel@linux.ibm.com>
Date:   Thu, 25 Jun 2020 17:18:37 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Tyler Hicks <tyhicks@...ux.microsoft.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc:     James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Prakhar Srivastava <prsriva02@...il.com>,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH 08/12] ima: Shallow copy the args_p member of
 ima_rule_entry.lsm elements

On Mon, 2020-06-22 at 19:32 -0500, Tyler Hicks wrote:
> The args_p member is a simple string that is allocated by
> ima_rule_init(). Shallow copy it like other non-LSM references in
> ima_rule_entry structs.
> 
> There are no longer any necessary error path cleanups to do in
> ima_lsm_copy_rule() so reference ownership from entry to nentry becomes
> easier.
> 
> Signed-off-by: Tyler Hicks <tyhicks@...ux.microsoft.com>
> ---
>  security/integrity/ima/ima_policy.c | 13 ++-----------
>  1 file changed, 2 insertions(+), 11 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index e33347148aa9..e9c7d318fdd4 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -306,10 +306,8 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
>  			continue;
>  
>  		nentry->lsm[i].type = entry->lsm[i].type;
> -		nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p,
> -						GFP_KERNEL);
> -		if (!nentry->lsm[i].args_p)
> -			goto out_err;
> +		nentry->lsm[i].args_p = entry->lsm[i].args_p;
> +		entry->lsm[i].args_p = NULL;

Nice.

>  
>  		security_filter_rule_init(nentry->lsm[i].type,
>  					  Audit_equal,
> @@ -325,13 +323,6 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
>  	entry->keyrings = NULL;
>  	entry->template = NULL;
>  	return nentry;
> -
> -out_err:
> -	nentry->fsname = NULL;
> -	nentry->keyrings = NULL;
> -	nentry->template = NULL;
> -	ima_free_rule(nentry);
> -	return NULL;
>  }

Definitely moving ima_free_rule() to the subsequent patch makes sense.

Mimi

>  
>  static int ima_lsm_update_rule(struct ima_rule_entry *entry)